Mastery of the art of archery is extremely difficult as many variables affect the accurate delivery of an arrow to the archer's desired target. The greatest variable is the accurate estimation of the distance the arrow is to travel to the target. An arrow moves relatively slow and falls to earth at an accelerating rate on its way to the target. This is the nature of archery and the trajectory of the archer's arrows requires extreme accuracy in range estimation by the archer in order to effectively place an arrow in a desired target, usually smaller than a dinner plate. The use of a sight pin in conjunction with a peep sight on the string of a bow can provide this accuracy if the exact range to the target can be ascertained.
Various bow sights have been shown for increasing the archers accuracy. U.S. Pat. No. 2,001,470 issued May 14, 1935 to Nyvall shows a folding bow with a top and bottom mirror acting as a periscope to reflect an image of the target to the eye of the archer. The lower mirror is rotationally articulated to align cross hairs on the lower mirror with the target. The lower mirror must be rotated to pre-arranged positions which relate to various distances which the archer must estimate by other methods.
U.S. Pat. No. 3,163,697 issued Dec. 29, 1964 to White shows a dual spaced mirror device arranged such that the viewer will simultaneously see both a real and a reflected target image. As a viewer looks at the target, a slide is manipulated until real and reflected images are both seen at the same height. At this position the bow is aimed at the target and is properly positioned such that an arrow will assume the proper trajectory to the target.
U.S. Pat. No. 3,524,440 issued Aug. 18, 1970 to Hill shows a mirror sighting device with an upper and lower mirror with cross hairs on one of the mirrors. The lower mirror is focused on the target while the upper mirror is focused on the lower mirror and reflects the target image to the archers eye. The mirror mounting the cross hairs may be adjusted vertically to compensate for distance to the target.
U.S. Pat. No. 2,788,701 issued Apr. 16, 1957 to Browning, shows a device incorporating multiple mirrors mounted below a single upper mirror for reflecting the image of the target and transmitting the image to the eye at various levels to facilitate trajectory adjustment of the bow for delivery of an arrow to the target.
U.S. Pat. No. 4,507,874 issued Apr. 2, 1985 to Brown, shows a bow sight characterized by a periscope device enclosing a top mirror and a bottom mirror to direct an image of a target to the eye of the archer. A compensating mirror is also mounted in the periscope in parallel adjustable relationship with respect to the top and bottom mirrors. A split target image is viewed in the fixed bottom mirror and comparison of this split image facilitates raising the bow to a proper angle in order to compensate for the trajectory of an arrow.
U.S. Pat. No. 4,555,856, issued Dec. 3, 1985 to Brown, is a continuation-in-part of the earlier '874 patent and shows a bow sight which includes, a housing enclosing a bottom mirror, a top mirror mounted in spaced relationship in the housing with respect to the bottom mirror and a narrow compensating mirror positioned in the housing in close proximity to the bottom mirror. The top and bottom mirrors are mounted in substantially parallel relationship at approximately a 45 degree angle in the housing and the top mirror and the compensating mirror are pivotally mounted with the compensating mirror adjustably responsive to manipulation of a lever from a calibrated position. The target image segment projected from the top mirror to the bottom mirror is compared to the target image segment projected from the compensating mirror to the bottom mirror and the lever is moved in order to provide the necessary adjustment to align the segments and determine a proper trajectory for accurately delivering an arrow to the target.
Numerous drawbacks have existed in the reliability and effective use of prior art sighting devices for archery bows. The need remains in the archery industry for a sight readily adaptable for long bows, recurve bows, compound bows, cross bows, and other similar projectile propelling devices of interest, which can accurately determine the distance between the viewer and the target and which can simultaneously adjust a sight pin to the proper trajectory for the arrow to the target. The primary goal of this invention is to fulfill this need.
Another further object of the invention is to provide a bow sight which is applicable to various bows and which uses a fixed bottom mirror and an adjustable top mirror in cooperation with an adjustable sight pin to determine the distance to the target and compensate for the arrow trajectory.
Yet another object of this invention is to provide an improved range finder device cooperating with a sighting device for various bows, which range finder device is characterized by a frame carrying a fixed bottom mirror and an adjustable top mirror pivotally mounted and cooperating with a horizontally moving sight pin whose cooperative movements are controlled by the shape of a programmable cam tangentially mounted on the rotational axis of the movable sight pin and whose design will adjust the arrow trajectory relative to the distance from the archer to the target when the archer views the split image composed of the real image and the reflected image and moves the operating lever which is geared to and cooperates the movable sight pin which also cooperates with the upper mirror adjusting lever. When the images are horizontally aligned the proper programmed cam movement has occurred and the sight pin has been moved to the proper position to deliver an arrow accurately to the target chosen by the archer.
A further object of the invention is to provide a range finder coupled bow sight of the character described and having various programmable cam sections which provide the exact movement between the range finder mirrors and the movable sight pin, which programmable cam is designed using the best known mathematical and geometrical relations and the desired trajectory necessary to accurately aim a bow and deliver an arrow to the desired target. Use of a preselected programmed cam section will therefore allow the archer to match the bow sight characteristics to the particular specifications of the archer's own equipment to accurately aim an arrow at a target within the effective range of the archer's bow.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.